Great question, and I like the logic, since normally everything 'resets' once it hits deck. However, it still doesn't work due to the way the rule is set up:
A unique character can only enter the field of battle once per turn. A unique character in a battle is protected from entering another battle via a band ability while it remains in battle. A unique character in a battle that leaves the battle is protected from entering any battle via a band ability until the end of the turn.
So it doesn't remember where a unique character is or where it went, the game "knows" what unique characters have hit battle, and they cannot enter battle any more in the same turn.